Improvement in apparatus for collecting- precious metals



.1. T. McDOUGALLQ Collecting Precious Metals.

Patented Nov. 10, 1868.

Dzm wfir Weases lfltt.

JAMES T. MCDOUGALL, OF SAN FRANCISCO, CALIFORNIA.

Letters Patent No. 83,868, dated November 10, 1868.

IMPROVEMENT IN APPARATUS FOR COLLECTING PRECIOU S METALS.

The Schedule referred to in theme Letters Patent and making part of the same.

To all whom it may concern..-

mining, and other places where water is used for washing the precious metals, so as to bring the gold or silver, or the float gold and silver, or float amalgam of the said precious metals, into contact with metallic copper, or other metals having afiinity for mercury,

and is intended as an improvement on an apparatus for collecting the precious metals, for which Letters Patent were granted to me," January 7, 1868, and 'numbered 73,021.

In constructing my improved apparatus, I place in my sluice-box a. plate of copper or other metal, the upper surface of which is either amalgamated, silvered, mercurialized, or in its natural condition. This plate is bent at right angles, to form theside plates. Upon the bottom of this plate, I place iron standards, having a square or oblong base, single or in sections, from which one or more stems or bars project upward. On the sides and corners of the bases there are projections, so that, when the standards are placed side by side, there are spaces between them. Loosely-fitting copper' tubes, with amalgamated surfaces, are placed over the projecting stems.

To more fully illustrate and describe my invention, reference is had to the accompanying drawings, and

letters marked thereon, 'of which Figure 1 is a side sectional elevation.

Figure 2 is a plan of my sluice.

Figure 3 is a view of one of the tubes, having vertical slots or openings.

Similar letters ofreferenoe indicate like parts in each of the figures.

A represents a sluice-box, formed, in the usual man-- nor, with a bottom and two side boards.

B is a metal plate, (I prefer to use copper,) bent so as to conform to the shape of the box, with bottom and sides of one sheet.

Along the bottom of this plate, I place iron standards, O O O O, having a square or oblong base, from which one or more stems or bars, D D, project upwards.

On the sides and cornersof the bases of the standards are projections, E E, so that, when they are placed side by side, open spaces will be lefitiietween them.

Where there is more than one standard, a narrow slit or opening,'F, is left midway betweer the stems,

which extends about half way across the base. opening,having no connecting outlet except below, serves, when filled with mercury, as a fountain of supply for the copper plate on which the stems rest.

It is intended that the standards shall cover the copper plate on the bottom of the box, excepting around the bases, where the interstices left by their peculiar form leave the plate exposed. These open spaces serve" as rifiles, and may be charged with mercury when desired,-the standards being so placed that the squares of the projecting stems will stand diagonally with the course of the running stream.

Loosely-fitting copper tubes, G G G, having amalgamated, silvered, or mercurialized surfaces, are placed over the projecting stems, and should be of suflicient length to reach the surface of the stream. The stems and tubes also serve as vertical riflles, and, when placed in rows across the running stream, convert it into eddies between each series of standards. v The particles of metal floating in the water, however buoyant they may are driven into the eddies, and, by the well-known whirlpool-movement, are subjected to a double impulse, a downward and outward movement from the vortex of the eddy, and the metal is brought into contact with the amalgamated surface, where it is retained.

When the running stream carries a large amount of stones or gravel, as where the apparatus is employed for placer-mining, so that the abrasion on the copper tubes would be too great, they may be dispensed with on the outside of the stems- In this case, the stems may be solid.

If desired, the copper tubes, bars, or other collectingapparatus, H, may be placed within the hollow of the stem H, .and communicate with the water outside through slots. or apertures, I I, in the iron or metal, shown at fig. 3, which exhibits a hollow stem.

When'the stems are solid, and without the copper caps or tubes, the collecting-surface relied upon is the copper plate, when exposed in the interstices between the standards. In this case, the stream in the sluice will be very shallow.

For cleaning up, when the copper tubes are employed, they may be removed, and the amalgam collected upon them is removed in the ordinary manner.

In the employment of my sluice-box, as above described, new and important improvements and principles in the/art of collecting the precious metals, when they are moving in a stream of running water, are shown; also, the advantages of a vertical riffle will be demonstrated, as well as the highly-important fact that, when iron, or copper apd iron in contact, are placed in moving water, and resting on plates of copper, having a mercurialized surface, the mercury (in the plate is not oxidized, but remains bright, and seizes the precious metals that come in contact with it with increased avidity. Whether the principle evolved be due to the electrical action incited, or produced by the This . serve as riffles when placed in running contact of metals having difi'erent degrees of latent heat, or electricity generated by the friction of the mine ning stream, or the greater affinity that the oxygen has for the iron, are questions not yet determined; but the fine particles of have heretofore run to waste for Want of a suitable device for collecting and retaining them, are here'saved.

Having thus described my invention, What I claim, and desire to secln'e by Letters Patent, is-

1. Vertical or inclining iron standards 0 O, with.

gold or metal and amalgam,'that- 3. iron stands, with hollow projecting stems, H, containing bars, slips, or tubes of copper, H, or other metal having afiinity for mercury, communicating with the water outside through slits or openings, I 1, substantially as described.

4. Copper resting on iron, the iron resting on copper, the copper having amalgamated, silvered, or mercurialized surfaces, when placed in sluice-boxes, or other apparatus, or equivalent device, designed to intercept and collect the precious metals moving with the water, in the manner and for the purposes herein specified.

5. The metallic obstructing and collecting-surfaces, or equivalent device, separately or in combination, whether placed in sluice-boxes, concentrators, or other apparatus for collecting the precious metals moving in running water, substantially as described.

and seal.

JAS. -'l. MODOUGALL. ,[L .-'s.] Witnesses:

GEO.' H. STRONG, G. W. M. SMITH.

In witness whereof, I have hereunto set my hand 

